London Irish prop Alex Corbisiero appears a major doubt for England's Six Nations opener against Scotland next month after suffering a fresh setback in his battle to overcome a knee injury.

Corbisiero was set to start his side's Premiership clash with Gloucester at Kingsholm earlier today but was a late withdrawal after his chronic knee problem flared up once again. The 24-year-old battled back to fitness to start England's recent clashes with South Africa and New Zealand but now looks a doubtful starter for the clash with the Scots at Twickenham on February 2.

"It is very frustrating for us, it is very frustrating for 'Corbs'. It is a tough time for him, and it is a difficult one to balance," commented London Irish director of rugby Brian Smith, following his team's 18-12 Kingsholm success. "His knee is a mess. He has played one-and-a-half games for us this season, and it is very disappointing.

"Sitting here right now, I couldn't tell you if he is going to play next week or not. He has got degenerative knee issues. He trained twice this week. We are bringing him back, and then at the captain's run he pulled out prior to it, and we had to make a change.

"There is not much of a decision to make when a bloke's knee has blown up and he feels he can't play. You can't put a gun to his head and tell him to get on the paddock. He is an honest person, he is a good bloke. He desperately wants to play for us, but it is a very frustrating situation."